Well I've been researching a lot for my upcoming Sydney trip ended up booking 2 different hotels one via rates to go and the other via Venere.com
I think it's best if you spend time searching on a few different sites because although I did find Venere.com the cheapest on average I did happen to find 1 hotel (that I ended up booking with) a lot cheaper than any other else on rates to go. Also even though (I think) all these sites are linked the eligible hotels (when using a promo code) seem to vary site by site.
Btw cheaptickets charge in USD. And If you do reach the $150 discount limit I suppose you could just break up the booking. Anyways hopefully it helps someone
Rules
Book a qualifying hotel between November 9, 2015 12:01AM CT and November 15, 2015 11:59PM CT, for 2 or more nights for travel between November 9, 2015 and March 31, 2016, via CheapTickets and instantly receive 20% off through the use of the promotion code. Limit one discount per hotel room and one promotion code up to a maximum savings of $150 per booking. Discount may not be used toward the booking of a vacation package. Discounts are not redeemable for cash for any reason. Promotion codes are non-transferrable, not for resale, and cannot be combined with other offers. Any attempt at fraud will be prosecuted to the fullest extent of the law. Void where prohibited, taxed or restricted. CheapTickets reserves the right to change or limit the promotion in its sole discretion. Most major chains are excluded, to find participating hotels look for "PROMO CODE ELIGIBLE" message.
FYI - Not working for anything in Singapore "We're sorry the promo code you entered is not valid for this destination"